Suppose we have a `MeshRegion` that we want to export to an obj file with, say double precision. Is that possible with `Export`? And how would we do that? The documentation on `"OBJ"` does not list any options. I am asking explicitly about `Export`. Of course, I could write my own OBJ exporter, but this would be somewhat awkward. (I've actually done it already.)

The default seems to export only about 6 decimal digits as the following example is supposed to show:

    R = MeshRegion[
       {{0., 0., 0.}, {Sqrt[2.], 0., 0.}, {0., Sqrt[2.], 0.}},
       Triangle[{{1, 2, 3}}]
       ];
    file = FileNameJoin[{$TemporaryDirectory, "a.obj"}];
    Export[file, R];
    MeshCoordinates[Import[file]] - MeshCoordinates[R]

> {{0., 0., 0.}, {-3.60048*10^-6, 0., 0.}, {0., -3.60048*10^-6, 0.}}

Btw.: Importing higher precision numbers with `Import` seems to work fine.